U.S. patent application number 14/124989 was filed with the patent office on 2014-04-24 for apparatus and methods to preserve catalyst activity in an epoxidation process.
This patent application is currently assigned to Momentive Specialty Chemicals Inc.. The applicant listed for this patent is Paul Haesakkers, Mark Kapellen, Prasad Muppa, Bert Van Den Bert. Invention is credited to Paul Haesakkers, Mark Kapellen, Prasad Muppa, Bert Van Den Bert.
Application Number | 20140113801 14/124989 |
Document ID | / |
Family ID | 46489157 |
Filed Date | 2014-04-24 |
United States Patent
Application |
20140113801 |
Kind Code |
A1 |
Kapellen; Mark ; et
al. |
April 24, 2014 |
APPARATUS AND METHODS TO PRESERVE CATALYST ACTIVITY IN AN
EPOXIDATION PROCESS
Abstract
Apparatus and methods are provided for forming and processing
multiphasic systems. In one embodiment, the invention provides a
process for the manufacture of an epoxide, including reacting an
olefinically unsaturated compound with an oxidant in the presence
of a buffer component and a water-soluble manganese complex
disposed in an aqueous phase having a first pH level in a first
multiphasic system, adjusting the pH of the aqueous phase to a
second pH level less than the first pH level, isolating at least a
portion of the aqueous phase from the first multiphasic system,
adjusting the pH of the at least a portion of the aqueous phase to
a third pH level greater than the second pH level, and introducing
the at least a portion of the aqueous phase into a second
multiphasic system.
Inventors: |
Kapellen; Mark;
(Vondelingenplaat, NL) ; Van Den Bert; Bert;
(Vondelingenplaat, NL) ; Muppa; Prasad;
(Vondelingenplaat, NL) ; Haesakkers; Paul;
(Vondelingenplaat, NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kapellen; Mark
Van Den Bert; Bert
Muppa; Prasad
Haesakkers; Paul |
Vondelingenplaat
Vondelingenplaat
Vondelingenplaat
Vondelingenplaat |
|
NL
NL
NL
NL |
|
|
Assignee: |
Momentive Specialty Chemicals
Inc.
Columbus
OH
|
Family ID: |
46489157 |
Appl. No.: |
14/124989 |
Filed: |
June 13, 2012 |
PCT Filed: |
June 13, 2012 |
PCT NO: |
PCT/EP2012/002527 |
371 Date: |
December 18, 2013 |
Current U.S.
Class: |
502/25 |
Current CPC
Class: |
C07D 301/12 20130101;
B01J 31/4092 20130101 |
Class at
Publication: |
502/25 |
International
Class: |
B01J 31/40 20060101
B01J031/40 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 22, 2011 |
EP |
11005091.1 |
Claims
1. A method for processing a multiphasic system comprising:
reacting an olefinically unsaturated compound with an oxidant in
the presence of a buffer component and a water-soluble manganese
complex disposed in an aqueous phase having a first pH level in a
first multiphasic system; adjusting the pH of the aqueous phase to
a second pH level less than the first pH level; isolating at least
a portion of the aqueous phase from the first multiphasic system;
adjusting the pH of the at least a portion of the aqueous phase to
a third pH level greater than the second pH level; and introducing
the at least a portion of the aqueous phase into a second
multiphasic system.
2. The process according to claim 1, wherein the reacting the
olefinically unsaturated compound with the oxidant in the first
multiphasic system comprises: adding the oxidant and the
water-soluble manganese complex as aqueous components to the first
multiphasic system; and dispersing the olefinically unsaturated
compound into the aqueous phase.
3. The process according to claim 1, wherein the isolating at least
a portion of the aqueous phase comprises retaining the
water-soluble manganese complex in the aqueous phase.
4. The process according to claim 1, wherein the first pH level is
from greater than 2.5 to 6.
5. The process according to claim 1, wherein the adjusting the pH
of the aqueous phase to the second pH level comprises inactivating
the water-soluble manganese complex.
6. The process according to claim 1, wherein the second pH level is
2.5 or less.
7. The process according to claim 1, wherein the adjusting the pH
of the aqueous phase to the second pH level comprises adding an
acid selected from the group oxalic acid, acetic acid, formic acid,
nitric acid, hydrochloric acid, sulphuric acid, and combinations
thereof.
8. The process according to claim 1, wherein adjusting the pH of
the at least a portion of the aqueous phase to the third pH level
comprises reactivating the water-soluble manganese complex.
9. The process according to claim 1, wherein the third pH level is
from greater than 2.5 to 6.
10. The process according to claim 1, wherein the adjusting the pH
of the aqueous phase to the third pH level comprises adding a base
selected from the group consisting of sodium hydroxide, potassium
hydroxide, calcium hydroxide, ammonium hydroxide, potassium
carbonate, sodium carbonate, potassium oxalate, sodium oxalate, and
combinations thereof.
11. The process of claim 1, wherein the first pH level and the
third pH level are the same pH level.
12. The process of claim 1, further comprising: reacting a second
olefinically unsaturated compound with a second oxidant in the
presence of a second buffer component and the water-soluble
manganese complex in an aqueous phase having the third pH level in
the second multiphasic system.
13. The process of claim 1, wherein the water-soluble manganese
complex has a first Turn Over Number rate from 2000 TON/hr to about
20,000 TON/hr at the first pH level, a second Turn Over Number rate
from about 0 TON/hr to less than 2000 TON/hr at the second pH
level, and a third Turn Over Number rate from 2000 TON/hr at the
third pH level.
14. The process of claim 1, wherein a time period between the
adjusting the pH of the aqueous phase to a second pH level and the
adjusting the pH of the aqueous phase to a third pH level is from
about 1 minute to about 120 minutes.
15. The process of claim 1, wherein the manganese complex
comprises: a mononuclear species of the general formula (I):
[LMnX.sub.m]Y (I), a binuclear species of the general formula (II):
[LMn(.mu.-X).sub.mMnL]Y.sub.n (II), or a polynuclear species of the
general formula (III): [L.sub.nMn.sub.n(.mu.-X).sub.m]Y.sub.n
(III), and wherein Mn is manganese; L or each L is independently a
polydentate ligand, each X is independently a coordinating species
and each .mu.-X is independently a bridging coordinating species,
wherein Y is a non-coordinating counter ion and m is from 1 to 4
and n is from 1 to 2.
16. The process of claim 15, wherein each coordinating species and
each bridging coordinating species is selected from the group
consisting of: RO.sup.-, Cl.sup.-, Br.sup.-, I.sup.-, F.sup.-,
NCS.sup.-, N.sub.3.sup.-, I.sub.3.sup.-, NH.sub.3, NR.sub.3,
RCOO.sup.-, RSO.sub.3.sup.-, RSO.sub.4.sup.-, OH.sup.-, O.sup.2-,
O.sub.2.sup.2-, HOO.sup.-, H.sub.2O, SH.sup.-, CN.sup.-, OCN.sup.-,
C.sub.2O.sub.4.sup.2-, and SO.sub.4.sup.2- and combinations
thereof, wherein R is a C.sub.1-C.sub.20 radical selected from the
group consisting of alkyl, cycloalkyl, aryl, benzyl and
combinations thereof, and Y comprises a non-coordinating counter
ion.
17. The process of claim 1, further comprising adding a second
manganese complex to the second multi-phasic system.
Description
FIELD OF THE INVENTION
[0001] The invention relates to the processing of a catalyst in a
multiphasic system and to an apparatus for carrying out the
processing of the catalyst.
BACKGROUND OF THE INVENTION
[0002] A process for the manufacture of a 1,2-epoxide is described
in the published European patent application EP 2149569. The
publication describes the catalytic oxidation of an olefinically
unsaturated compound using a water soluble manganese complex as the
oxidation catalyst. The process described is carried out in a
multiphasic system, such as a biphasic system, having an organic
phase, which may be a liquid or a gaseous phase, and an aqueous
phase. The actual reaction is believed to take place in the aqueous
phase, and the resulting epoxide product separates from the aqueous
phase into the organic phase due to low solubility of, or
extraction or stripping by the organic phase. For this reason, the
1,2-epoxide is produced of a desirable turnover number (TON), with
a desirable selectivity towards the 1,2-epoxide, while providing an
improved ease of isolating the produced 1,2-epoxide.
[0003] While the epoxide product is recovered in the organic phase
through a phase separation process, it was observed that the
manganese complex is retained in the aqueous phase. Unfortunately,
attempts to recover and/or recycle the manganese complex have met
with limited success as the manganese complex was observed to
deactivate during phase separation when the aqueous phase is not
intensively mixed with the organic phase.
[0004] Therefore, there is a need for a process and apparatus for
recovery or recycling of the manganese complex catalyst system.
SUMMARY OF THE INVENTION
[0005] Accordingly, the invention provides for processing a
manganese complex between epoxidation reactions without a loss or
with a minimal loss in catalytic activity by adjusting a phase
containing the manganese complex to a pH level that reduces the
deactivation of the manganese complex when not used as catalyst in
a reaction, and then at a later time, adjusting the pH of the phase
containing the pH to epoxide reaction conditions for use as a
catalyst.
[0006] In one embodiment, the invention provides a method for
processing a multiphasic system including reacting an olefinically
unsaturated compound with an oxidant in the presence of a buffer
component and a water-soluble manganese complex in an aqueous phase
having a first pH level in a first multiphasic system, adjusting
the pH of the aqueous phase to a second pH level less than the
first pH level, isolating at least a portion of the aqueous phase
from the first multiphasic system, adjusting the pH of the at least
a portion of the aqueous phase to a third pH level greater than the
second pH level, and introducing the at least a portion of the
aqueous phase into a second multiphasic system.
[0007] In one embodiment, the invention provides an apparatus for a
method for processing a multiphasic system including a first
reactor adapted to process a multiphasic system, wherein the first
reactor has a first outlet line, a second reactor adapted to
process a multiphasic system, wherein the second reactor has a
second outlet line, one or more component tanks independently
fluidly coupled to each of the first reactor and the second
reactor, a first phase separator disposed between the first reactor
and the second reactor, wherein the phase separator comprises an
organic phase outlet line and an aqueous phase outlet line and the
first phase separator is fluidly coupled to the first outlet line
and is fluidly coupled to the second reactor by the aqueous phase
outlet line, an acid-containing line fluidly coupled to the first
outlet line between the first reactor and the phase separator, the
phase separator, or combinations thereof, and a base-containing
line coupled to the phase separator outlet line between the phase
separator and the second reactor, the second reactor, or
combinations thereof.
[0008] The apparatus may further include a third reactor adapted to
process a multiphasic system, wherein the third reactor has a third
outlet line, one or more component tanks independently fluidly
coupled to the third reactor, a second phase separator disposed
between the second reactor and the third reactor, wherein the phase
separator is fluidly coupled to the second outlet line and is
fluidly coupled to the third reactor by a second phase separator
aqueous phase outlet line, a second acid-containing line fluidly
coupled to the second outlet line between the second reactor and
the second phase separator, the second phase separator, or
combinations thereof, and a second base-containing line coupled to
the second phase separator outlet line between the second phase
separator and the third reactor, the third reactor, or combinations
thereof.
DETAILED DESCRIPTION OF THE FIGURES
[0009] The following is a brief description of figures wherein like
numbering indicates like elements.
[0010] FIG. 1 illustrates a schematic representation of an
embodiment of a device for the processing of a catalyst;
[0011] FIG. 2 illustrates a graph of a series of process results
from one embodiment of the process described herein; and
[0012] FIG. 3 illustrates a graph of a series of process results
from another embodiment of the process described herein.
DETAILED DESCRIPTION OF THE INVENTION
[0013] As used in the current specification, the expressions
"epoxidation" and "oxidation" refer to the same reaction; the
conversion of the carbon-carbon double bond of the olefinically
unsaturated compound into an oxirane ring. The invention is
hereafter discussed in greater detail. Chemical compounds having an
oxirane ring are described herein as epoxide compounds.
[0014] The following description refers to Turn Over Number (TON)
and Turn Over Frequency. As described herein the Turn Over Number
refers to the number of moles of substrate that a mole of catalyst
can convert before becoming deactivated. In particular, for the
processes described herein Turn Over Number may refer to the number
of moles of the olefinically unsaturated compound that a mole of
the manganese complex can convert before becoming deactivated
[0015] As described herein, Turn Over Frequency is the number of
moles of the substrate being converted (turnover) by the catalyst
in a period of time. As the Turn Over Frequency changes over time,
the Turn Over Frequency can be represented by the Turn Over Number
(TON) per unit of time, dTON/dt. In particular, Turn Over Number
(TON) is calculated or measured by the temperature difference (dT)
between the reaction mixture and the cooling medium as a measure of
epoxidation rate, which translates into dTON/dt.
[0016] As used herein, "deactivation" is a process in which the
complexes as described herein are reduced to the individual
components with reduced or minimal complex structure retention, and
have no or significantly reduced catalytic activity. Deactivation
is observed when the catalytic activity, as measured by Turn Over
Frequency (dTON/dt) is below 1000 TON/hour (TON/hr), such as from
about 0 TON/hr to about 500 TON/hr. The UV-Vis data also
illustrates reduces or minimal absorbance between wavelengths 250
to 350 nm (Table 7), which indicates the absence of a coordinate
manganese in a oxidation state of Mn.sup.3+ (III) or Mn.sup.4+
(IV).
[0017] As used herein, "inactivation", is a process wherein the
complexes described herein remain intact as complexes without
deactivation in an aqueous medium. Inactivation of the catalytic
activity, as measured by Turn Over Frequency is below 2000 TON/hr,
such as from about 100 TON/hr to about 1000 TON/hr. The UV-Vis data
illustrates absorbance between wavelengths 250 to 350 nm (Table 7)
with a new and less intense visible absorption at 425 nm. This less
intense absorption at 425 nm indicates that the manganese is in a
3+ oxidation state with the transformation of the active
Mn.sup.3+-catalyst to a catalytically inactive manganese complex
for an epoxidation process.
[0018] As used herein, "reactivation", is a process wherein the
inactive complexes described herein are chemically activated
without loss of catalytic activity or with no significantly reduced
catalytic activity, compared to the active complexes prior to
inactivation, to perform as catalyst in a reaction mixture.
Reactivation of the catalytic activity, as measured by Turn Over
Frequency, is from 2000 TON/hr to about 20,000 TON/hr. The UV-Vis
data also illustrates that the absorbance between wavelengths
250-350 nm, and the disappearance of visible absorbance at 425 nm
(Table 7), indicates that the manganese is in a 3+ oxidation state
and remains a catalytically active manganese complex for an
epoxidation process.
[0019] Loss of UV-Vis absorbance at 350, 400, and 425 identifies
the deactivated catalyst. Active and inactive catalysts display
good absorbance at 350, 400 and 425 nm and are attributed to
Mn.sup.3+-species. Inactive Mn.sup.3+-catalysts species are
differentiated from the Mn.sup.3+-active catalysts
(Mn.sup.III-active catalysts) from the increased absorbance at 425
nm as shown in Table 7 below.
[0020] In one embodiment, the invention provides for processing a
composition having manganese complex (as a catalyst) by using the
manganese complex in an epoxidation reaction, inactivating the
manganese complex in the composition, and then reactivating the
manganese complex for use in another epoxidation reaction.
[0021] It was surprisingly and unexpectedly discovered that the
Turn Over Frequency of the manganese complex can be significantly
reduced while the deactivation of the manganese complex does not
occur or is significantly reduced when the pH of a reaction mixture
or aqueous phase containing the manganese complexes is reduced to a
pH of 2.5 or less. This surprising result was found since the
ligands as described herein, with the exception of Cu2+ complexes
of the ligands, are thermodynamically unstable at a pH level below
4 in the range of relevant catalyst concentrations. Additionally,
the result was also surprising since it has been observed that at
lower pH levels, complexes of such ligands have accelerated
deactivation (de-complexation). Thus, the process described herein
is based on the observation that a manganese complex may be
catalytically inactivated while maintaining the manganese complex
structure, and then reactivated for use as a catalyst at a later
time.
[0022] The epoxidation process is carried out in a multiphasic
system of an aqueous phase and at least one organic phase. The
epoxidation process as described herein includes reacting an
olefinically unsaturated compound with an oxidizer in the presence
of a manganese complex as a catalyst, with an optional buffer
component, in an aqueous medium at acidic conditions. The oxidation
of the olefinically unsaturated compound is believed to take place
in an aqueous phase, whereas the organic phase is believed to
extract or strip produced 1,2-epoxide from the aqueous phase.
[0023] The pH of the epoxidation reaction is from greater than 2.5
to about 6, such as from about 2.8 to about 5.0, for example, from
about 3 to about 3.6. The manganese complex of the epoxidation
reaction may have a catalytic activity, as measured by Turn Over
Frequency, from 2000 TON/hr to about 20,000 TON/hr, such as from
about 2000 TON/hr to about 10,000 TON/hr.
[0024] The resulting system, or reaction mixture, may then be
processed to allow the respective phases of the reaction mixture to
settle into separable phases, such a separate aqueous phase and at
least one separate organic phase. For example, the reaction mixture
may be discharged from a reactor, with the discharged reaction
mixture comprising both product and unreacted starting material, to
a separator to settle into the aqueous phase containing the
complexes described herein and the organic phase containing the
epoxide product described herein. For example, the at least one
organic phase may comprise two organic phases, with one organic
phase comprising an epoxide product and a second organic phase
comprising an organic reactant. It has been observed that the
organic phase contains little or no water soluble by-products and
catalyst.
[0025] The separated aqueous phase was observed to have the
manganese complex in a catalytically active state. The pH of the
separated aqueous phase is from greater than 2.5 to about 6, such
as from about 2.8 to about 5.0, for example, from about 2.8 to
about 3.8.
[0026] The manganese complex was further observed to accelerate
deactivation when retained in the isolated aqueous phase.
[0027] Without being bound to any theory, it is believed that the
presence of olefinically unsaturated compound allows the catalyst
to remain active without accelerated deactivation, whereas it is
believed that without the presence of olefinically unsaturated
compound and/or due to the presence of the epoxide and/or oxidant
without olefinically unsaturated compound present, the activity of
the active catalyst reduces an accelerated rate.
[0028] It was surprisingly and unexpectedly discovered by the
inventors, that the manganese complex may be retained in the
aqueous phase without deactivation or with reduced deactivation of
the manganese complex to the constituents by using a pH more acidic
than the epoxidation process. This result was found to be
surprising and unexpected since it is known in the art that lower
pH levels lead to accelerated deactivation (de-complexation).
[0029] The manganese complex may be retained in the aqueous phase
with no or minimal deactivation by reducing the pH of the aqueous
phase to 2.5 or less, such as from about 1 to about 2. The pH of
the aqueous phase may be reduced by the addition of a first pH
adjusting agent, such as an acid, such as an inorganic acid, an
organic acid, or combinations thereof. Suitable organic acids may
include such as oxalic acid, acetic acid, formic acid, and
combinations thereof, while suitable inorganic acids may include
hydrochloric acid (HCl) sulphuric acid (H.sub.2SO.sub.4), nitric
acid, and combinations thereof.
[0030] The inactivated manganese complex may be retained in the
aqueous phase with no or minimal deactivation for a period of time
from about 1 minutes to about 120 minutes, such as from about 5
minutes to about 60 minutes, for example, from about 5 minutes to
30 minutes. The inactivated manganese complex may have a catalytic
activity, as measured by Turn Over Frequency, from about 0 TON/hr
to less than 2000 TON/hr, such as from about 100 TON/hr to about
1000 TON/hr.
[0031] The manganese complex in the aqueous phase may then be
reintroduced into or form a mixture containing the components for
an epoxidation reaction with the aqueous phase having the pH
adjusted to have the manganese complex in a catalytically active
state. This may be achieved by increasing the pH of the aqueous
medium to a pH from greater than 2.5 to about 6, such as from about
2.8 to about 3.8.
[0032] The pH may be adjusted by the addition of a second pH
adjusting agent. The second pH adjusting agent may be an inorganic
base, an organic base, or combinations thereof. Examples of
suitable bases include compounds selected from the group of sodium
hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide
(Ca(OH).sub.2), ammonium hydroxide (NH.sub.4OH), aliphatic amines,
potassium carbonate, sodium carbonate, potassium oxalate, sodium
oxalate, and combinations thereof.
[0033] The reactivated manganese complex may have a catalytic
activity, as measured by Turn Over Frequency, from 2000 TON/h to
about 20,000 TON/h, such as from about 2000 TON/h to about 10,000
TON/h. In terms of water-soluble manganese complexes that may be
used as oxidation catalyst, many suitable complexes are known. Note
in this respect that what is described in this patent is actually
the catalyst precursor. Indeed, in all open and patent literature
typically a catalyst precursor is defined, as the active species
during the system may be different and in fact even changing during
the reaction that it catalyzes. For convenience sake, and as this
is common in the literature, we refer to the complex as if the
complex is the catalyst.
[0034] The manganese complex (catalyst) as described herein may be
a mononuclear manganese complex, a binuclear manganese complex, or
a polynuclear complex. Examples of such complexes include:
[0035] a mononuclear species of the general formula (I):
[LMnX.sub.m]Y (I);
[0036] , a binuclear species of the general formula (II):
[LMn(.mu.-X).sub.mMnL]Y.sub.n (II), or
[0037] a polynuclear species of the general formula (I):
[L.sub.nMn.sub.n(.mu.-X).sub.m]Y.sub.n (III),
and a combination of the complexes, where Mn is manganese; L or
each L is independently a polydentate ligand. Each X is
independently a coordinating species and each .mu.-X is
independently a bridging coordinating species, selected from the
group consisting of: RO.sup.-, Cl.sup.-, Br.sup.-, I.sup.-,
F.sup.-, NCS.sup.-, N.sub.3.sup.-, I.sub.3.sup.-, NH.sub.3,
NR.sub.3, RCOO.sup.-, RSO.sub.3.sup.-, RSO.sub.4.sup.-, OH.sup.-,
O.sup.2-, O.sub.2.sup.-, HOO.sup.-, H.sub.2O, SH.sup.-, CN.sup.-,
OCN.sup.-, C.sub.2O.sub.4.sup.2-, and SO.sub.4.sup.2- and
combinations thereof, wherein R is a C.sub.1-C.sub.20 radical
selected from the group consisting of alkyl, cycloalkyl, aryl,
benzyl and combinations thereof. The manganese constituent may be
in the oxidation states of +2 or +3 or +4. In the formulas, m may
be from 1 to 3, for example 3, and n may be from 0 to 3, such as 1
or 2.
[0038] Y is a non-coordinating counter ion. The non-coordinating
counter ion Y may provide for the charge neutrality of the complex
and the value of n depends upon the charge of the cationic complex
and anionic counter ion Y. Counter ion Y may for instance be an
anion selected from the group consisting of RO.sup.-, Cl.sup.-,
Br.sup.-, I.sup.-, F.sup.-, SO.sub.4.sup.2-, RCOO.sup.-,
PF.sub.6.sup.-, tosylate, triflate (CF.sub.3SO.sub.3.sup.-) and a
combination thereof with R once again being a C.sub.1 to C.sub.20
radical selected from the group consisting of alkyl, cycloalkyl,
aryl, benzyl and combination thereof. The type of anion is not very
critical, although some anions are more preferred than others. In
one embodiment, an ion of CH.sub.3COO.sup.- or PF.sub.6.sup.- may
be used as the non-coordinating counter ion.
[0039] Polydentate ligands are multiple bond ligands capable of
forming a coordination complex or metal complex. Suitable
polydentate ligands include acyclic compounds containing at least 7
atoms in the backbone or cyclic compounds containing at least 9
atoms in the ring, each having the nitrogen atoms separated by at
least two carbon atoms. A suitable class of ligands include
1,4,7-triazacyclononane ("Tacn") and substituted versions thereof.
The substituted 1,4,7-triazacyclononane compound may be substituted
with one or more organic groups having a C.sub.1 to C.sub.20
organic group selected from the group consisting of alkyl,
cycloalkyl, aryl, and combination thereof. For example,
1,4,7-triazacyclononane, may be substituted by one or more methyl
groups, to form N',N'',N'''-trimethyl-1,4,7-triazacyclononane
(TmTacn). Examples of suitable ligands include compounds selected
from the group of N',N'',N'''-trimethyl-1,4,7-triazacyclononane,
1,5,9-trimethyl-1,5,9-triazacyclododecane (1,5,9-Me.sub.3TACD),
2-methyl-1,4,7-trimethyl-1,4,7-triazacyclononane (2-Me,
1,4,7-Me.sub.3TACN), 2-methyl-1,4,7-triazacyclononane, and
combinations thereof.
[0040] In one embodiment of the manganese complex, the manganese
complexes are those of the formula
[Mn.sup.IV.sub.2(.mu.-O).sub.3L.sub.2](Y).sub.n (same as formula:
[LMn(.mu.-O).sub.3MnL](Y).sub.n), wherein n is 2, and L and Y have
the meaning identified above, such as TmTacn as ligand, and
PF.sub.6.sup.- or acetate (CH.sub.3CO.sub.2.sup.-, hereinafter OAc)
as counterion. The catalyst system comprising a water soluble
manganese complex is described above. One complex for the current
invention comprises 1,4,7-trimethyl-1,4,7,-triazacyclononane
("TmTacn") as the ligand or ligands. This ligand is commercially
available from Aldrich.
[0041] Additionally, the manganese complex may be formed in situ
from the reaction of a free ligand and a source of manganese. The
free ligand may be the ligand described herein. The manganese
source may comprise any manganese salt suitable having manganese
ions in the oxidation state of Mn.sup.2+ (II). Suitable manganese
salts may include manganese salts of organic acids, inorganic
acids, or a combination thereof. Examples of suitable manganese
salts include salts selected from the group consisting of manganese
sulphate, manganese acetate, manganese nitrate, manganese chloride,
manganese bromide, and combinations thereof. The manganese source
may be provided as a solid or dissolved in an aqueous medium.
[0042] The water-solubility of the manganese complex formed is a
function of all the aforementioned components and depending on the
counter ion (anion) associated with the manganese complex. The
manganese complex may have a water solubility of about 1 g/L or
greater at 20.degree. C., for example, from about 1 g/L to about 2
g/L at about 20.degree. C.
[0043] The manganese complex may be used with the components for an
epoxidation reaction to produce an epoxide product. The epoxidation
process includes reacting an olefinically unsaturated compound with
an oxidizer in the presence of a manganese complex as a catalyst,
with an optional buffer component, in an aqueous medium at acidic
conditions. Depending on the reactants and reaction type, the
epoxidation process may be carried out at a temperature in the
range from about -5.degree. C. to about 60.degree. C., such as from
about 4.degree. C. to about 40.degree. C., for example, from about
5.degree. C. to about 35.degree. C. Moreover, the process may be
carried out at reduced pressure or under increased pressure, such
as from 0.1 bars to 20 bars, such as from 0.9 bars to 9 bars. For
instance, a higher pressure may be used when propylene is
epoxidized.
[0044] The epoxidation reaction may be performed in a homogenous
biphasic system with the organic phase distributed in the aqueous
phase. The organic phase may be distributed in the aqueous phase
through a process such as agitation. The phase ratio by volume of
the two phases may be a volume ratio of organic to aqueous phase
from about 5:1 to 1:10, such as from about 1:1 to about 1:2.
[0045] It has been observed that improved epoxide product
conversion rates may be achieved by the use of olefinically
unsaturated compounds that have limited solubility in water, for
example, allyl chloride and allyl acetate instead of conventionally
used allyl alcohol. The multiphasic system may be created by adding
the olefinically unsaturated compound with limited solubility to an
aqueous phase in an amount greater than what dissolves in the
aqueous phase. Suitable olefinically unsaturated compounds may have
a maximum solubility of about 100 g/L (at 20.degree. C.), such as
from 0.01 g/L to 100 g/L at 20.degree. C.
[0046] According to the invention, the olefinically unsaturated
compound used is an epoxidizible olefin which may be
functionalized. The olefinically unsaturated compound may be a
liquid under process conditions, for example, allyl chloride or
liquefied propylene, but also a gas, for example, gaseous
propylene.
[0047] Examples of suitable olefinically unsaturated compounds
include olefinically unsaturated compounds. In one embodiment, the
olefinically unsaturated compound may have at least one unsaturated
--C.dbd.C-- bond, such as at least one unsaturated --C.dbd.CH.sub.2
group. The olefinically unsaturated compound may comprise more than
one unsaturated --C.dbd.C-- bond. Moreover, the unsaturated
--C.dbd.C-- bond need not be a terminal group. Terminally
olefinically unsaturated compounds may have one or more terminal
--C.dbd.CH.sub.2 bonds.
[0048] Suitable examples of olefinically unsaturated compound
therefore include the following compounds:
R--CH.dbd.CH.sub.2;
R'--(CH.dbd.CH.sub.2).sub.n;
X--CH.dbd.CH.sub.2;
Y--(CH.dbd.CH.sub.2).sub.2;
wherein R is a radical of 1 or more carbon atoms optionally
comprising 1 or more heteroatoms (such as oxygen, nitrogen or
silicon); R' is a multivalent radical of 1 or more carbon atoms
optionally comprising 1 or more heteroatoms wherein n corresponds
with the valence of the multivalent radical; X is a halogen atom,
and Y is an oxygen atom.
[0049] Of particular interest are olefinically unsaturated
compounds selected from the compounds vinylhalides or allylhalides,
such as vinylchloride or allylchloride; 1-alkenes, such as propene;
a cycloalkene, including aromatic compounds; mono-, di- or
polyallyl ethers of mono-, di- or polyols; mono-, di- or polyvinyl
ethers of mono-, di- or polyols; mono-, di- or polyallyl esters of
mono-, di- or polyacid; mono-, di- or polyvinyl esters of mono-,
di- or polyacids; divinylethers or diallylethers; and combinations
thereof.
[0050] In another embodiment of the present invention, the
olefinically unsaturated compound is selected from allyl bromide,
allyl chloride and allyl acetate. In another embodiment of the
invention allyl chloride is used for the manufacture of
epichlorohydrin, because of the commercial interest and ease of
isolating the produced epichlorohydrin.
[0051] According to another embodiment of the present invention the
olefinically unsaturated compound is propylene in order to produce
propylene oxide, and the reaction may be carried out at
temperatures in the range from -5.degree. C. to 40.degree. C.
Propylene may be used in excess over the oxidant.
[0052] The epoxidation process may use oxidizers including
oxygen-containing gases, inorganic peroxides, organic peroxides,
peracids, permanganates, hydrogen peroxide precursors, and
combinations thereof. The oxidizer may be provided at a
concentration from about 0.05 wt. % to about 4 wt. %, such as from
about 0.1 wt. % to about 3 wt. %, for example, from about 0.3 wt. %
to about 2 wt. % of the composition. Suitable oxygen-containing
gases include oxygen gas (O.sub.2), atmospheric air, and
combinations thereof. Suitable inorganic peroxides include, for
example, hydrogen peroxide, sodium peroxide, urea hydroperoxide,
and combinations thereof. Hydrogen peroxide precursors may include
metals used to form hydrogen peroxide from hydrogen gas and oxygen
gas.
[0053] For example, hydrogen peroxide may be used as the oxidizer.
Hydrogen peroxide may be used in an aqueous solution at a
concentration that may vary, from 15% to 98% (propellant grade),
such as industrial grades varying from 20 to 80%, for example, from
30 to 70%. Hydrogen peroxide precursors may include metals used to
form hydrogen peroxide from hydrogen gas and oxygen gas.
[0054] The epoxidation process is performed in an aqueous reaction
medium (again, excluding any olefins and/or the corresponding
oxides dissolved therein) that is essentially a 100% water
phase.
[0055] In an alternative embodiment, the epoxidation processes may
be performed with organic solvents in the aqueous phase. The
current epoxidation process may be carried out in an aqueous
reaction medium comprising 10 volume percent or less of
co-solvents. The use of organic co-solvents, such as water-soluble
alcohols, is believed to improve the solubility of the olefinically
unsaturated compound. Suitable co-solvents include, for example,
acetone, methanol, and other water-soluble alcohols. Examples of
co-solvents include, for example, acetone, acetonitrile, methanol,
tetra hydrofuran (THF), and combinations thereof. The amount of
organic co-solvents may be reduced to a minimum and the reaction
may be carried out in a reaction medium substantially composed of
water. With the exclusion of the presence of the reactants and the
epoxidation products, the aqueous reaction medium therefore
suitably comprises at least 90% by volume of water (v %), such as
at least 95 v %, for example, at least 99 v %, and in some
embodiments, at least 99.9 v % of water. The aqueous reaction
medium (again, excluding any olefins and/or the corresponding
oxides dissolved therein) may be essentially a 100% water
phase.
[0056] The manganese complex is used in catalytically effective
amounts. Typically, the catalyst is used in a molar ratio of
catalyst (Mn) to the oxidant of from 1:10 to 1:10,000,000, such as
from 1:100 to 1:1,000,000, for example, from 1:1000 to 1:100,000.
As a matter of convenience the amount of catalyst may also be
expressed in terms of its concentration, when keeping in mind the
volume of the aqueous medium. For instance, it may be used in a
molar concentration (based on the Mn) of from about 0.001 to about
10 mmol/L, such as from about 0.01 to about 7 mmol/L and for
example, from about 0.01 to about 2 mmol/L.
[0057] The molar ratio of olefinically unsaturated compound for the
process of the current invention includes a molar ratio of
olefinically unsaturated compound to oxidant that may be greater
than 1:2. This ratio may be in the range of from about 1:1 to about
12:1. For example, the molar ratio may be about 1:1, about 1.2:1,
about 2:1, or about 4:1, or in the range of 2:1 to 12:1. If too
much oxidant is used, then the selectivity towards the 1,2-epoxide
reduces due to the production of undesirable side-products. Another
consequence of too much oxidant with respect to olefinically
unsaturated compound is rapid catalyst deactivation. If not enough
oxidant is used, then the turnover number is suboptimal. This is
therefore significantly different from bleaching conditions
described in the prior art, where excessive amounts of oxidant,
i.e. hydrogen peroxide are used. To ensure optimal peroxide
efficiency, the oxidant may be added to the aqueous phase at a rate
about equal to the reaction rate of the catalytic oxidation.
[0058] The reaction (catalytic oxidation) of the olefinically
unsaturated compound takes place in the aqueous phase. The aqueous
phase may have a pH from about 1 to about 8, such as from about 2
to about 6, for example from about 3 to about 5.
[0059] The aqueous phase may further comprise a buffer system to
stabilize the pH in a certain range. While the following component
is referred to as a buffer component, the component may also
function or be utilized as a co-catalyst, a bridging ion, and/or a
co-ligand, as described herein for the respective components.
[0060] The pH may be stabilized in an acidic pH range of greater
than 2.5 to less than 7, such as a pH level range between about 2.8
and about 6, for the epoxidation reaction. The pH is therefore
(well) below that used when bleaching olefins with hydrogen
peroxide as the oxidant, typically carried out at more alkaline
conditions (for example, pH adjusted with NaHCO.sub.3 to 9.0).
[0061] The buffer component may be used in a molar ratio to the
manganese complex (catalyst) in the range from about 1:1 to about
17, 000:1, such as from about 1:10 to about 1:1000. Sufficient
buffer component may be added to produce the second pH level. In
some embodiments, the concentration of the buffer component in the
aqueous phase may range from about 0.05 wt % to about 9 wt %, such
as from about 0.1 wt % to about 1 wt %. According to still another
embodiment of the invention, the buffer, if any, and oxidation
catalyst are fed as a pre-mixed mixture.
[0062] The buffer component may comprise an acid or an acid with
the corresponding acid salt, such as an organic acid-salt
combination. Suitable acids include with aliphatic or aromatic
organic acids, such as oxalic acid, acetic acid, citric acid and
aromatic acids based on substituted benzoic acids, and combinations
thereof; inorganic acids, such as hydrochloric acid, phosphoric
acid, and combinations thereof; and combinations thereof. Suitable
acid-salt combinations may be selected from the group of oxalic
acid-oxalate salt, hydrochloric acid-sodium citrate, oxalic
acid-oxalate salt, malonic acid-malonate salt, succinic
acid-succinate, glutaric acid-glutrate, acetic acid-acetate salt,
citric acid-citrate salt, disodium phosphate-monosodium phosphate,
4-chlorobutanoic acid-4-chlorobutanoate, ortho-chloro benzoic
acid-salt, para-chloro benzoic acid-salt, ortho-flouoro benzoic
acid-salt, para-fluoro benzoic acid-salt, and combinations
thereof.
[0063] The aqueous phase may further comprise a phase transfer
agent and/or a surfactant. The phase transfer agent and/or a
surfactant may be used if an olefinically unsaturated compound has
low solubility (for example, below 0.1 g/L water). Phase transfer
agents that may be used in the process of the invention include
quaternary alkyl ammonium salts. Surfactants that may be used in
the process of the invention include non ionic surfactants such as
Triton X100.TM. available from Union Carbide.
[0064] The reaction conditions for the catalytic oxidation may be
quickly determined by a person skilled in the art. The reaction is
exothermic, and cooling of the reaction mixture may be required.
The reaction may be carried out at temperatures anywhere from
-5.degree. C. to 40.degree. C., dependent upon such physical
parameters as melting and boiling point of the used olefinically
unsaturated compounds.
[0065] The epoxidation reaction is further performed under
agitation or mixing conditions. For example, the epoxidation
reaction may be performed in a reactor having a stirring disposed
therein or in a loop reactor having a mixing component disposed
before and/or within the loop reactor lines. The amount of
agitation will vary based on the epoxidation process, and the
invention contemplates that sufficient agitation is performed to
provide for performing the process as described herein to provide
results as described herein.
[0066] According to one embodiment of the invention, the
epoxidation reaction is performed in a reactor having an inlet and
an outlet. Reaction components as described herein are fed to the
reactor by one or more inlets, and the resulting multiphasic
system, or reaction mixture, is discharged though the outlet. The
processing apparatus further includes a separating means, such as a
separator, connected to the reactor outlet for separating the
reaction mixture into the at least one organic phase and the
aqueous phase as explained above. This separation means may
comprise a straight forward liquid to liquid separator, such as a
settling tank, since the product forms at least one separate
organic phase and the organic phase separates from the aqueous
phase when allowed to settle. Other devices such as hydrocyclones
can also be used for separating the phases.
[0067] Prior to introduction into the separator or in the separator
itself, the aqueous phase of the reaction mixture may be modified
as described herein, to inactivate the manganese complexes of the
catalyst system.
[0068] The aqueous phase may then be introduced into a second
reactor or recycled into the original reactor. Inside the reactor
or prior to introduction into the reactor, the aqueous phase of the
reaction mixture may be modified as described herein, to reactivate
the manganese complexes of the catalyst system.
[0069] The present invention is further explained by means of FIG.
1, which shows a schematic representation of an embodiment of a
device for the manufacture of epoxide products and manganese
complex processing.
[0070] It is noted here that the skilled person facing the task of
constructing the device for carrying out the process according to
the invention, will be aware that all process technological
elements of the device are constructed and operated by using common
general process technological knowledge.
[0071] In this embodiment, the apparatus 10 comprises one or more
reactors. The reactors may be a variety of reactors adapted to
perform epoxidation reactions, such as multiphase loop reactors as
mentioned herein. Several reactor designs are suited to carry out
the process according to the invention. The reactor may be a plug
flow reactor (PFR). Due to the required high velocity for
dispersing and the long residence times a PFR used in the present
invention will be a very long PFR. The reactor may also be a
continuous stirred tank reactor (CSTR). When using a CSTR, special
care should be taken in dispersing the olefinically unsaturated
compound into the aqueous phase. The reactor type will also include
a cooling means for controlling the temperature of the catalytic
oxidation process.
[0072] According to one embodiment of the invention, the catalytic
oxidation may also be carried out in a loop reactor. In a loop
reactor, the reaction mixture is circulated. When the circulation
rate of the loop reactor is about 15 times the rate at which the
aqueous components and the olefinically unsaturated compound is
fed, such as the feed rate, the loop reactor may be described as a
CSTR because of the high degree of back mixing. The advantage of
using a loop reactor in the present process is that it allows for
the well defined mixing behaviour of a pumped system combined with
dispersing means in a compact reactor design.
[0073] The reactor according to the invention further comprises
dispersing means for dispersing the organic olefinically
unsaturated compound phase into the aqueous phase and cooling means
for controlling the temperature of the catalytic oxidation, because
of its exothermic nature.
[0074] The dispersing means may be a static mixer, since it is
believed that a static mixer will provide maximum break up of
organic droplets in the continuous aqueous phase. According to
another embodiment of the invention fresh oxidant and olefin are
fed to the aqueous phase in subdivided portions to the reactor
through multiple inlet parts distributed over the reactor
housing.
[0075] For illustrative purposes, the apparatus 10 is shown as
having three reactors referenced as reactors 20, 30, and 40 of FIG.
1. Each reactor contains a series of component inlet lines, for
example, as shown in FIG. 1, the series of component inlet lines
fqr the reactor 20 include inlet lines 21, 22, 23, and 24, and an
outlet line, such as outlet line 25 as shown in the FIG. 1. The
respective inlet lines are coupled to respective component feed
lines, such as feed lines 11, 12, 13, and 14. While not shown, each
component feed line is coupled to a separate feeding tank to feed
components into the respective reactors. For example, feed lines
11, 12, 13, and 14, may respectively be the manganese complex feed
line 11, the olefinically unsaturated compound (such as allyl
chloride) feed line 12, the oxidizer (such as hydrogen peroxide)
feed line 13, and the buffer component feed line 14. The components
are transported from the feeding tanks to the respective reactor
through the respective lines by means of feeding pumps (also not
shown).
[0076] The reaction mixture is discharged from the reactor 20 via
the reactor outlet line 25 into a separating means 50. A first pH
adjusting line 26 may be coupled to the reactor outlet line 25
between the respective reactor and the respective separating means.
The first pH adjusting line 26 may be coupled to a source line 15
of an acid or a suitable acid/acid salt mixture or the buffer
component feed line 14 (not shown), which source material may be
used to reduce the pH of the fluid traveling through the reactor
outlet line 25 prior to arriving at the separating means 50.
Alternatively, the first pH adjusting line 26 is coupled to the
separating mean 50 directly, shown as dotted line 26a.
[0077] In the separating means 50, such as a separator, the at
least one organic phase and the aqueous phase are allowed to form
distinct phases. The organic phase comprising an epoxide product,
such as epichlorohydrin, is allowed to separate and then may be
isolated from the separating means 50 through the product outlet
52, which is coupled to a product retrieval line 56.
[0078] At least part of the aqueous phase in the separating means
50 is reused. In one example the aqueous phase is delivered to a
second reactor 30 via a conduit 54 connecting the separating means
50 and the second reactor 30. In an alternative embodiment, while
not shown, the aqueous phase from the separator may be recycled
back to the reactor 20. Additionally, and also not shown,
additional aqueous phase containing the manganese complex, whether
in an activated or inactivated state, such as from line 21 or
another reactor's aqueous phase, may be mixed with the material in
conduit 54 prior to addition to the reactor 30. A cycling pump (not
shown) transports the aqueous phase through the cycling
conduit.
[0079] A second pH adjusting line 31 is coupled to the conduit 54
between the respective separator means and the reactor.
Alternatively, the second pH adjusting line 31 is coupled to the
second reactor. The second pH adjusting line 31 contains a base as
described herein that may be used to increase the pH of the aqueous
phase prior to addition to the reactor. The second pH adjusting
line 31 may also be a branch line from the main base feed line 14
as shown in FIG. 1.
[0080] The processes described herein may be continued using a
second separator 60 and third reactor 40 for recycling the aqueous
phase through another reaction process. The second separator 60 is
fed from outlet line 35, and a pH adjusting line 36 is coupled to
the outlet line 35, or alternatively to the reactor 40 by line 36a.
An epoxide product exits the separator through the product outlet
62, which is coupled to a product retrieval line 56. The aqueous
phase is delivered to the third reactor 40 via a conduit 64
connecting the separating means 60 and the third reactor 40. The
third reactor 40 also includes product inlet lines 42, 43, and 44,
and outlet line 45.
[0081] Additionally, an optional manganese complex replenishment
line 70 may be coupled to subsequent reactors, such as lines 71 for
reactor 30 and line 72 for reactor 40. The replenishment line 70
provides manganese complex, and optionally the buffer, to the
reactor to provide that the reactor has sufficient amounts of
manganese complex for catalyzing the epoxidation reaction. As the
process described herein provides for the preservation or reduced
deactivation of the manganese complex, the replenishment process
may be required to replace the manganese complex that has already
deactivated from the prior reaction.
[0082] The transfer means to any of the reactors may be achieved by
the use of fluid conduit. For example, for recycling, the transfer
means may be a pipe connecting an aqueous phase outlet of the
separation means and a reactor inlet equipped with a pump to
transport the aqueous phase into the originating reactor. For
delivering the aqueous phase to a second reactor the transfer means
may be a pipe connecting an aqueous phase outlet of the separation
means and a second reactor's inlet equipped with a pump to
transport the aqueous phase into the second reactor. It is noted
here that the skilled person will be aware that the reactor
according to the invention is equipped with standard process
technological elements like for example, pumps, valves and control
mechanisms.
[0083] In operation, the apparatus may be used as follows with the
process described herein. While the following description
illustrates the epoxidation of an allyl chloride, the invention
contemplates that the process and any of the components described
herein may be used in the apparatus described herein.
[0084] Initially, the olefinically unsaturated compound, such as
allyl chloride, the oxidizer, such as hydrogen peroxide, and the
manganese complex as described herein are charged with water to a
reactor, such as reactor 20. A buffer component, such as a buffer
of oxalic acid/oxalate salt may also be charged into the reactor.
The components may be introduced simultaneously, periodically or
sequentially into the reactor. The components are allowed to react
and produce an epoxide component in a reaction mixture, such as
epichlorohydrin from allyl chloride, as described herein. The
reaction mixture may be multiphasic, such as at least one organic
phase and one aqueous phase. The epoxide component will separate
out into at least one of the organic phases. It is believed that is
some embodiments, the organic precursor material, such as
epichlorohydrin may form a second and separate organic phase from
the epoxide containing organic phase.
[0085] The volumetric ratio of the organic phase to the aqueous
phase, both inside the respective reactor, and the degree of
contact between the phases are important parameters in the
performance of the catalyst system. If the amount of organic phase
is too high, the aqueous phase is no longer the continuous phase.
In this case, there may be insufficient mixing of the ingredients.
This means that the conversion rate of olefinically unsaturated
compound is considerably lowered. On the other hand, if the aqueous
phase inside the reactor is too high with respect to the amount of
organic phase, the olefinically unsaturated compound concentration
in the aqueous phase will be too low with respect to oxidant
concentration. This may lead to the production of undesirable side
products and catalyst deactivation. Therefore the volumetric ratio
of aqueous phase to organic phase inside the reactor may be in the
range of from 10:1 to 1:5, with emulsion formation as a maximum
limit.
[0086] The above limitations can also be influenced by the degree
of mixing. In practice this means that the organic phase needs to
be well dispersed into the continuous aqueous phase, such as in the
form of droplets, preferably as small as possible, for example,
less than 3 mm. Upon dispersion of the organic phase into the
aqueous phase, the reaction (catalytic oxidation) of the
olefinically unsaturated compound and the oxidant in the presence
of the catalyst may occur.
[0087] The reaction mixture is then transported to a separating
means 50 via a reactor outlet line 25. A first pH adjusting agent
from the first pH adjusting line 26 may be added to the reaction
mixture in the reactor outlet line 25 or the separating means 50.
The first pH adjusting agent may be an acid, such as an acid used
in forming the buffer component described herein. Sufficient first
pH adjusting agent may be added to adjust the pH to a level of less
than 2.5, as described herein. Suitable organic acids may include
such as oxalic acid, acetic acid, and combinations thereof, while
suitable inorganic acids may include hydrochloric acid (HCl)
sulphuric acid (H.sub.2SO.sub.4), and combinations thereof. The
adjustment of the pH is believed to allow the manganese complex to
be retained in the aqueous phase with no or minimal deactivation of
the manganese complex.
[0088] In the separating means 50, the organic phase comprising an
epoxide product, such as epichlorohydrin, may be isolated from the
aqueous phase by removal of the organic phase through the product
outlet 52.
[0089] The remaining aqueous phase in the separating means 50 may
be reused by feeding at least a portion (part) of the separated
aqueous phase to a next reactor or by recycling at least a portion
of the separated aqueous phase to the prior reactor. The at least a
portion of the aqueous phase may be cycled into the reaction
mixture. This way, catalyst present in the cycled aqueous phase is
not discharged and efficiently used again.
[0090] The aqueous phase may be cycled to the next reactor, such as
reactor 30, by a cycling conduit 54 connecting the separating means
50 and the next reactor 30. A second pH adjusting line 36 for a
second pH adjusting agent is coupled to the cycling conduit 54
between the respective separator means and the reactor.
Alternatively, the second pH adjusting line 36 is coupled to the
respective reactor. The second pH adjusting agent may be a base as
described herein. Sufficient second pH adjusting agent may be added
to adjust the pH to a level of 2.5 or greater. Suitable second pH
adjusting agents include a base, for example, selected from the
group consisting of group of sodium hydroxide (NaOH), potassium
hydroxide (KOH), calcium hydroxide (Ca(OH).sub.2), ammonium
hydroxide (NH.sub.4OH), and combinations thereof. The adjustment of
the pH is believed to allow the manganese complex to be retained in
the aqueous phase with no or minimal deactivation of the manganese
complex.
[0091] When the process is running, per unit time, certain volumes
of aqueous starting materials, such as the oxidant, catalyst and,
if needed, buffer, are supplied to the reaction mixture.
[0092] These aqueous starting materials are indicated as the
aqueous components. Simultaneously, per unit time, also a certain
volume of separated aqueous phase is cycled into the reaction
mixture. The mass ratio of the volume of aqueous components to the
volume of recycled aqueous phase added to the reaction mixture at
every instant is indicated as the water recycle ratio. In order to
achieve the advantageous effects of recycling the catalyst, said
water recycle ratio may be in the range of from about 10:1 to about
1:10, such as from about 2:1 to about 1:5 and for example, about
1:3.5. Also, turbulent conditions such as a high velocity of the
aqueous phase will prevent agglomeration of the organic droplets
dispersed in said medium.
[0093] The following experiments illustrate the processes for the
manganese complex as described herein.
Experimental Set Up:
[0094] The experiments were carried out in a jacketed glass batch
reactor on 200 ml scale. The reaction mixture includes an organic
phase containing the olefinically unsaturated compound and a water
phase containing the manganese complex, the buffer component, and
the oxidant, in which the oxidant is fed continuously. By stirring
the organic mixture, the organic phase, is finely dispersed in the
water phase where it reacts with hydrogen peroxide. The reactor is
equipped with temperature control and pH control.
Experiment 1
[0095] A process was performed as described above. First, a
reference experiment was performed in which the temperature was
maintained at 5.degree. C., and the pH controlled at 3.6. To 100 mL
of water, 164 mg disodiumoxalate and 72 mg anhydrous oxalic acid
was added. To this buffer solution, 0.203 mL of 3.5 wt % Dragon
A350 (manganese complex) was added and stirred for 10 minutes. To
the water phase, 100 mL allyl chloride was added. The allylchloride
was dispersed in the water phase for 5 more minutes. Then, at t=0,
hydrogen peroxide was dosed for 150 minutes according to the dosing
schedule in Table 1 below. From t=0 to t=210, a 5 wt % oxalic acid
solution in water was dosed at a flow rate of 6 mL/h. For pH
control, 0.5 M NaOH was used.
TABLE-US-00001 TABLE 1 Time (minutes) 35 wt % H.sub.2O.sub.2 (mL/h)
0-25 10 25-30 20 30-50 15 50-85 10 85-150 7 150-210 0
[0096] The above reference experiment was repeated three times, in
which at t=60 the pH was changed to a secondary value, such as 1.5,
2.5 and 3.6 respectively, by dosing a 2 M HCl solution until the
desired pH was reached. Then, H.sub.2O.sub.2 dosing and stirring
were stopped for one hour to simulate the conditions in a settler
with a residence time of one hour, thereby allowing the water and
organic phases to settle.
[0097] After one hour, stirring was started; the pH adjusted back
to 3.6 using the pH control and H.sub.2O.sub.2 dosing was started
again according to the above dosing schedule. The result of an
identical experiment as a reference reaction at a pH of 3.6 without
settling was also performed. The reference reaction and the three
reactions with settling were then plotted as Turn Over Number (TON)
versus time as shown in FIG. 2
[0098] FIG. 2 illustrates that the reaction settling at pH=3.6 has
a TON rate of 700 TON/hr, indicating that settling at a pH of 3.6
results in deactivation of the catalyst with minimal catalytic
activity in a subsequent epoxidation reaction after settling. The
experimental data for a pH of 1.5 and a pH of 2.5 indicate that
settling at such pH levels has minimal effect on the catalyst
activity compared to the reference without settling as shown in
Table 2 below. The values in this table give the average TON/h
after settling until t=210 compared to the reference between t=60
and t=150.
TABLE-US-00002 TABLE 2 Turn Over Frequency Reaction Type TON/hr
Reference 6603 After Settling at pH = 1.5 5144 After Settling at pH
= 2.5 5472 After Settling at pH = 3.6 705
[0099] The final turn over numbers for the settling at pH values of
pH 1.5 and 2.5 are only slightly lower than the reference, as shown
in Table 3 below.
TABLE-US-00003 TABLE 3 Turn Over Frequency Reaction Type TON/hr
Reference 20112 After Settling at pH = 1.5 18479 After Settling at
pH = 2.5 18739 After Settling at pH = 3.6 11641
[0100] Thus, as shown in FIG. 2 and Tables 2 and 3, the process
described herein has resulted in the manganese complexes
substantially maintaining the respective catalytic activity, with
reduced or minimal deactivation of the manganese catalyst
Experiment 2
[0101] A process was performed as described above. First, a
reference experiment was performed in which the temperature was
maintained at 15.degree. C., and the pH controlled at 3.6. To 100
mL of water, 164 mg disodiumoxalate and 72 mg anhydrous oxalic acid
was added. To this buffer solution, 0.203 mL of 3.5 wt %
[Mn.sub.2O.sub.3(MeTACN).sub.2](OAc).sub.2 (Dragon A350 manganese
complex) was added and stirred for 10 minutes. To the water phase,
100 mL allyl chloride was added. The allylchloride was dispersed in
the water phase for 5 more minutes. Then, at t=0, hydrogen peroxide
was dosed for 180 minutes according to the dosing schedule in Table
4 below. From t=0 to t=210, a 5 wt % oxalic acid solution in water
was dosed at a flow rate of 10 mL/h. For pH control, 0.5 M NaOH was
used.
TABLE-US-00004 TABLE 4 Time (minutes) 35 wt % H.sub.2O.sub.2 (mL/h)
0-6 10 6-15 18 15-40 13 40-80 9 80-150 6 150-180 5 180-210 0
[0102] The above reference experiment was repeated two times, in
which at t=45 the pH was changed to a secondary value, such as 2.0
and 2.5 respectively, by dosing a 2 M HCl solution until the
desired pH was reached. Then, H.sub.2O.sub.2 dosing and stirring
were stopped for 30 minutes to simulate the conditions in a settler
with a residence time of 30 minutes.
[0103] After 30 minutes, stirring was started, the pH adjusted back
to 3.6 using the pH control and H.sub.2O.sub.2 dosing was started
again according to the above dosing schedule. The reference
reaction and the two reactions with settling were then plotted as
Turn Over Number (TON) versus time as shown in FIG. 3.
[0104] FIG. 3 illustrates that settling at pH of 2.0 gives better
results in terms of TON/h and final TON, indicating less catalyst
deactivation as compared to a pH of 2.5. The experimental data for
settling at pH of 2.0 and 2.5 indicate that settling at such pH
levels has a reduced or minimal effect on the catalyst activity
compared to the reference without settling as shown in Table 5
below. The values in this table give the average TON/h after
settling until t=210 compared to the reference between t=45 and
t=180.
TABLE-US-00005 TABLE 5 Turn Over Frequency Reaction Type TON/hr
Reference 5040 After Settling at pH = 2.0 5054 After Settling at pH
= 2.5 4255
[0105] The final turn over number is only slightly lower than the
reference, as shown in Table 6 below.
TABLE-US-00006 TABLE 6 Turn Over Frequency Reaction Type TON/hr
Reference 20665 After Settling at pH = 1.5 20195 After Settling at
pH = 2.5 18270
[0106] Manganese complexes at various pH levels were subjected to
an UV-Vis spectra analysis during the manganese complex forming
process. The UV-Vis analysis includes an in-line spectral analysis
of the mixture during the process of the active catalyst
preparation and with the application of various pH levels. The
UV-Vis analysis is performed with an UV-V is spectrometer supplied
by Avantes Company B.V. Halogen lamp is used as light source with
the wavelengths range from 210 to 600 nm. Water was used as an
internal reference to collect the UV-Vis spectra of the mixture at
designated intervals of time during the catalyst preparation. An
in-line probe is placed in the reactor in order to collect the
spectra during the preparation of the catalyst and also to see the
changes of the catalyst at various pH levels.
[0107] The UV-Vis spectra were used to determine the type of the
catalyst species such as catalyst precursor, active catalyst,
inactive catalyst (at low pH) and the deactivated catalyst with the
measurement of Intensity/Absorbance in arbitrary unit versus
wavelengths of manganese complex. The manganese complex absorbs
wavelengths in the range of 250 nm to 350 nm, and the extent of the
absorbance corresponds to the amount of manganese complex. The
Mn-TMTACN catalysts of Mn.sup.3+ and Mn.sup.4+-TMTACN
(Mn.sup.IV-TMTACN) complexes display UV-Vis spectra with strong
absorptions between 250 to 350 nm accompanied by weak absorptions
400 and 500 nm. Thus, the Intensity/Absorbance at around 350 nm
correspond to the amount of manganese complex.
[0108] The UV-Vis spectral data of the aqueous solution was
obtained in a model experiment by the changes in the pH in order to
mimic the epoxidation reactions explained in Examples 2 and 3. The
UV-Vis spectra of aqueous solution containing catalyst precursor
[Mn.sub.2L.sub.2O.sub.3](OAc).sub.2 at 0.24 mmol/L, oxalate buffer
at 48 mmol/L and H.sub.2O.sub.2 at 11 mmol/L in water are measured
at 5.degree. C. from 200 to 600 nm.
[0109] The reaction was started at stage (i) with the stirring of
catalyst precursor, oxalate and dilute H.sub.2O.sub.2 at 5.degree.
C., and this step was carried out for an hour. In the second step,
stage (ii), the pH of the reaction mixture was reduced to 2.4 and
stayed for 1 hour under stirring conditions. In the third step,
stage (iii), the pH was increased again to 3.8 and continued the
reaction for 2 hours. Measurements were performed at these three
distinct stages and found different catalyst species. They are
essentially catalyst precursor at pH of 3.8 at the start of stage
(i), an active catalyst at 0.5 hours time period of stage (i), an
inactive catalyst species at a pH of 2.4 in stage (ii), and the
deactivated catalyst at the end of the stage (iii) at a pH of 3.8.
Table 7 as follows illustrates the respective UV-Vis data for the
activated, deactivated, and inactivated manganese complexes.
TABLE-US-00007 TABLE 7 Active Inactive Wavelength Precursor
catalyst catalyst Deactivated (nm) (Mn.sup.4+) (Mn.sup.3+)
(Mn.sup.3+) catalyst 350 0.58 0.58 0.58 0.02 400 0.31 0.18 0.22
0.01 425 0.21 0.18 0.24 0 500 0.12 0.1 0.07 0
[0110] At the start of the stage (i), catalyst precursor was
observed to have a manganese complex of Mn.sup.4+ in the aqueous
solution. An active catalyst species was formed at 0.5 hours time
period in stage (i) at a pH of 3.8, which was observed to have a
manganese complex of Mn.sup.3+, and in the stage (ii) an inactive
catalyst at a pH of 2.4 was formed which is also observed to
contain manganese in the oxidation state +3. Oxalate and dilute
H.sub.2O.sub.2 were helped to reduce the catalyst precursor
(Mn.sup.4+) to an active catalyst (Mn.sup.3+) in the first step.
When the pH was adjusted to a pH of 2.4, the active
Mn.sup.3+-catalyst was converted into an inactive catalyst species
during period held at the lower pH. After one hour, the inactive
catalyst species composition at pH 2.4 was adjusted to a pH of 3.8
and found that all the inactive catalyst is converted back into
Mn.sup.3+ active catalyst. The Mn.sup.3+-active catalyst at pH 3.8
converted slowly into deactivated catalyst in a span of 2
hours.
[0111] All catalyst species at stages (i), (ii) and (iii) were
observed to have near identical absorbencies of about 0.58
intensity (arbitrary units) at the wavelength of 350 nm. The
similar absorbencies indicate that the amount of the manganese
complexes was maintained and exhibit minimal if no deactivation
during the pH adjustments. Additionally, the inactive catalyst
species at stage (ii) was observed to maintain the same
absorbencies from the initial pH adjustment through the one hour pH
hold period. Such an indication corresponds to the stability of the
amount of manganese complex in the pH 2.4 adjusted composition over
a period of time with minimal or no indication of deactivation.
Also, a quantitative conversion of inactive catalyst species in
stage (iii) back to the active catalyst was observed based on the
same absorbencies from the pH adjustment through the one hour pH
hold period. At the end of the step (iii) the catalyst is converted
into deactivated catalyst in 2 hour time period.
[0112] Catalyst precursor (Mn.sup.+4) displayed two weak visible
absorptions at around 400 and 500 nm along with an intense charge
transfer band (CT band) from 250-350 nm. Conversion of catalyst
precursor to active catalyst (Mn.sup.3+) in stage (i) is evident
from the decrease of the intensity of two weak visible absorptions.
When the pH was reduced to 2.4, the active catalyst was converted
into a Mn.sup.3+-inactive catalyst. Presence of inactive species is
evident from the appearance of visible absorption at 425 nm with
the maintenance of same concentration based on the absorption at
350 nm. Temporary inactive species at stage (ii) at a pH of 2.4 are
quantitatively reversible back to the active catalyst species when
the pH is raised to above 3.8.
[0113] While the present invention has been described and
illustrated by reference to particular embodiments, those of
ordinary skill in the art will appreciate that the invention lends
itself to variations not necessarily illustrated herein.
* * * * *